1. Field of the Invention
The field of the invention relates to roll changing apparatus and, more particularly, to means for cutting and transferring a moving web to a new core without stopping the movement of the web.
2. Prior Art
A variety of roll changing apparatus are available in the art for use on both surface winding and center winding machines for the purpose of cutting a continuously moving web and transferring the leading edge of the cut web to a new core. Such devices are illustrated, for example, in U.S. Pat. Nos. 4,058,267; 3,871,595; 3,734,423; and 3,383,062. In each of these devices the cutting blade is driven into the web in order to effect cutting of the web. With modern day winding equipment, however, this manner of cutting the web has become undesirable for several reasons.
The web on modern winding equipment is moving much faster than older equipment, and much of the web material now being wound is more elastic and tends to stretch over the knife blade than was the case with previous materials. As web speeds increase, the speed of the knife as it moves through the web must also increase in order to sever the web at the exact point desired. Failure to sever the web at the right point results in an undesirably long leading edge of web which, when it begins to roll about the new core, often folds back on itself which is undesirable. Likewise, more elastic material is difficult to sever at the exact point desired since it tends to stretch over the knife blade as it is being cut and thus also produces an undesirably long leading edge which folds back on the roll.
One method proposed of overcoming this undesirable fold back produced by most prior art roll changing devices is disclosed in U.S. patent application Ser. No. 165,301, filed July 2, 1980, now U.S. Pat. No. 4,326,679, and assigned to the same Assignee as the present invention. In that device and method the blade is moved into a location adjacent the web and held in a stationary position during the web cutting operation. The web is then moved into the knife blade which produces a cut at the exact point on the web desired so that little or no fold back occurs as the leading edge is transferred to the new core. The present invention is an improvement of that device in that it reduces the necessary parts in the apparatus and provides a somewhat different method of achieving the desirable result of no fold back roll changing.